基于遥感与现场观测数据的南海北部内波传播速度

ON PROPAGATION VELOCITY OF INTERNAL SOLITARY WAVES IN THE NORTHERN SOUTH CHINA SEA WITH REMOTE SENSING AND IN-SITU OBSERVATIONS DATA

南海北部是全球海洋中内波最为活跃、生成和演变机制较为复杂的海域,本文利用多源卫星遥感数据(MODIS、GF-1、ENVISAT ASAR、RADARSAT-2)和现场观测数据开展了南海北部内波传播速度的研究。通过匹配捕获同一条内波的相邻两幅遥感图像,由内波的空间位移和时间间隔反演传播速度,并以0.5°×0.5°网格给出了南海北部内波传播速度的分布图。研究结果表明,内波传播速度受背景流场、水体层结和底地形变化等多因素影响,特别是水深。在南海北部由东至西、由南至北方向,内波传播速度逐渐递减。深海区内波传播速度最大,可达3m/s以上;内波在向西大陆架传播过程中,随着水深变浅速度逐渐减慢,传播速度为1—2m/s;大陆架浅海的内波传播速度较小,仅为零点几米每秒。同时,利用Kd V方程反演了内波传播速度理论值,对遥感数据提取的内波传播速度进行了精度验证,结果较为一致。

The northern South China Sea（NSCS） is a hot spot of the internal waves. Internal waves in the NSCS are very complex because of complicated generation and evolution mechanism. We studied the propagation velocity of the internal solitary wave（ISW） in the NSCS with multi-sourced remote sensing satellite data（MODIS, GF-1, ENVISAT ASAR, and RADARSAT-2） and in-situ observation data. The propagation velocity was derived using horizontal displacement of ISW patterns and the time difference between satellite image pairs. The distribution of propagation velocity was presented in 0.5°×0.5° grid in the NSCS. The results show that the propagation velocity is affected mainly by water depth, as well as the water temperature, stratification, and the bottom terrain. The propagation velocity decreases gradually westwards and northward in NSCS from 3 m/s in the deep sea to 1 m/s in the shallow continental shelf. Meanwhile, the propagation velocity obtained from satellite images is in good agreement with the theoretical calculations using the Kd V equation.